Fibre laser joining of highly dissimilar materials: Commercially pure Ti and PET hybrid joint for medical device applications

Laser transmission joining (LTJ) is growing in importance, and has the potential to become a niche technique for the fabrication of hybrid plastic-metal joints for medical device applications. The possibility of directly joining plastics to metals by LTJ has been demonstrated by a number of recent studies. However, a reliable and quantitative method for defining the contact area between the plastic and metal, facilitating calculation of the mechanical shear stress of the hybrid joints, is still lacking. A new method, based on image analysis using ImageJ, is proposed here to quantify the contact area at the joint interface. The effect of discolouration on the mechanical performance of the hybrid joints is also reported for the first time. Biocompatible polyethylene terephthalate (PET) and commercially pure titanium (Ti) were selected as materials for laser joining using a 200 W CW fibre laser system. The effect of laser power, scanning speed and stand-off distance between the nozzle tip and top surface of the plastic were studied and analysed by Taguchi L9 orthogonal array and ANOVA respectively. The surface morphology, structure and elemental composition on the PET and Ti surfaces after shearing/peeling apart were characterized by SEM, EDX, XRD and XPS.

What now for the contact hypothesis? Towards a new research agenda

This article begins with a review of recent research on the Contact Hypothesis. It will be shown that the literature in this area has become essentially closed and self-referential where the core political and theoretical premises that underpin the Hypothesis have been taken for granted and the debates have therefore become restricted simply to how best to measure the influence of inter-group contact. One of the key reasons for this is the lack of critical engagement with the Contact Hypothesis from those of a more structuralist and/or ‘radical’ perspective. This may be because the individualistic focus of the Hypothesis is seen from such a perspective as largely irrelevant to addressing racial and ethnic divisions and/or because it may be felt that to engage with the concept is to give it undue legitimacy. It will be argued in this article, however, that the wholesale dismissal of the Contact Hypothesis is a little premature. Just as recent research on racial and ethnic divisions has drawn attention to the way in which such divisions exist at a number of layers within the social formation – from the structural, political and ideological through to the sub-cultural, interactional and biographical – so must any initiatives aimed at addressing these divisions be similarly ‘multi-layered’ in their approach. However, it will be argued that for research to help inform specific strategies at the interactional level, there needs to be a significant change in the way that inter-group contact, and the Contact Hypothesis more generally, is studied. The article will ‘model out’ one potentially fruitful way in which such research can develop through the use of an ethnographic case study involving a cross-community scheme arranged for Protestant and Catholic children in Northern Ireland.

Effect of contact pressure on fretting fatigue behavior of Ti-1023

With a new test facility, we have investigated fretting fatigue properties of Ti-1023 titanium alloy at different contact pressure. Both fatigue fracture and fretting scar were analyzed by scanning electron microscopy (SEM). Moreover, the depth of crack initiation area in fatigue fracture has been analyzed quantitatively, to investigate the relationship between the depth of crack initiation area and the fretting fatigue strength. The changing trends of the depth of crack initiation area and fretting fatigue strength with the increase of contact pressure show obvious opposite correlations. The depth of crack initiation area increases rapidly with the increase of contact pressure at low contact pressure (smaller than 10 MPa), and the fretting fatigue strength drops rapidly. At the contact pressure of 10–45 MPa, both the depth of crack initiation area and the fretting fatigue strength do not vary significantly. Contact pressure influences fatigue strength through influencing the initiation of fatigue crack. The main damage patterns are fatigue flake and plow.

By our tongues united? Irish and Scots language contact in rural Ulster

This article suggests that the impact of long-term language contact between the languages of Irish, Scots and English in the province of Ulster led to a hybridisation of accent which challenges traditional ethnolinguistic differentiations - namely, the myth that Catholics and Protestants can be differentiated by their accent. The digitisation of archive recordings from the Tape Recorded Survey of Hiberno-English (TRSHE) permitted a detailed phonetic analysis of two speakers from Atticall, a rural townland in the Mourne Mountains with a unique geographical and linguistic setting, due to the close proximity of Ulster Scots and Irish speakers in the area. Phonological features associated with Irish, Northern English and Lowland Scots were garnered from previous dialectological research in Irish, English and Scots phonologies, which aided with the interpretation of the data. Other contemporaneous recordings from the TRSHE allowed further comparison of phonological features with areas of Ulster in which linguistic interaction between Scots and Irish was expected to be less prevalent, such as Arranmore, Donegal (primarily Irish) and Glarryford, Antrim (primarily Scots). Accommodation theory and substrate/superstrate interaction illuminate patterns of phonological transfer in Mourne, Arranmore and Glarryford English, supporting the conclusion that accent in contemporary Northern Ireland is built upon a linguistic heritage of contact and exchange, rather than political or ethnolinguistic division

Mobile Phones and Contact Arrangements for Children Living in Care

This article reports the findings from the first UK study to examine the use of mobile phones by looked after children. Contact with family and friends is important, but it has sometimes to be carefully managed to avoid unintended consequences such as placement instability. The study examined the ways in which mobile phone technology impacts on contact, drawing on the experiences of children and young people in foster-care and residential care, and of policy makers, social workers, foster parents and residential care staff. No guidance was available that addressed the issue of mobile phone contact arrangements for looked after children and young people. Three years on from the start of the study, this remains the case in the area where the study was conducted, resulting in variation in the way mobile phone use for contact is managed; the issue appears only to be specifically addressed when identified as a problem. The position of mobile phone facilitated contact as a recognised form of contact requires review. The evidence suggests it should routinely form part of children’s care plans, and that residential staff and foster parents need to be adequately prepared and supported for the dynamics of mobile phone facilitated contact.